434 research outputs found
Numerical Simulations of Intermittent Transport in Scrape-Off Layer Plasmas
Two-dimensional fluid simulations of interchange turbulence for geometry and
parameters relevant for the scrape-off layer of confined plasmas are presented.
We observe bursty ejection of particles and heat from the bulk plasma in the
form of blobs. These structures propagate far into the scrape-off layer where
they are lost due to transport along open magnetic field lines. From
single-point recordings it is shown that the blobs have asymmetric conditional
wave forms and lead to positively skewed and flat probability distribution
functions. The radial propagation velocity may reach one tenth of the sound
speed. These results are in excellent agreement with recent experimental
measurements.Comment: 8 pages, 7 figure
Complications of canine tonsillectomy by clamping technique combined with monopolar electrosurgery – a retrospective study of 39 cases
BackgroundCanine tonsillectomy is performed due to acute or chronic tonsillitis, neoplasia, trauma or occasionally brachycephalic obstructive airway syndrome. Several tonsillectomy techniques are used but information about surgical complications is scarce. This retrospective study of patient records at the University Animal Hospital aimed to investigate complications related to canine tonsillectomy performed by 20-min clamping combined with monopolar electrosurgery.Inclusion criteria were bilateral tonsillectomy performed with “20-min clamping technique combined with monopolar electrosurgery without suture or ligation”. Exclusion criteria were unilateral tonsillectomy, tonsillar neoplasia, additional surgical procedures other than tonsillectomy, cases where sutures were used initially, and cases where unspecified or other methods of tonsillectomy were used. The search of the patient records of the University Animal Hospital included a 10-year period. Complications that required additional anaesthesia were defined as major complications. Minor complications were handled during surgery or after surgery without surgical intervention.ResultsOf 39 dogs that fulfilled the inclusion criteria, 11 dogs had complications and out of those 1 dog had two complications. Altogether, of the 12 complications, 2 were classified as major complications and 10 as minor.The most frequent complication was bleeding from the surgical site, in total 11 incidences; 10 dogs had an incidence of bleeding and out of those, 1 dog bled twice, both during and after surgery. Of these 10 dogs that bled, seven incidences of bleeding occurred during surgery and four incidences occurred after surgery. The two dogs with major complications were re-anaesthetized due to bleeding after surgery. No lethal complications occurred and all dogs survived to discharge.ConclusionsBleeding during and after surgery was a common complication in dogs after bilateral tonsillectomy using “20-min clamping technique combined with monopolar electrocautery”. Revision intervention was often needed, sometimes urgently. Although no comparison was made with another technique, the studied technique should be used with caution
Longitudinal stability augmentation of seaplanes in planing
The towing tank experiments conducted at Yokohama National University from November 30 to December 9 in 2005 suggested a new way of suppressing a dangerous coupled motion between heave and pitch called porpoising. The research in this paper was developed on the observations made in the experiments and conducted numerical simulations to further investigate the parametric design space. Two linear-time-invariant models were developed: rigid-body planing craft (conventional float planes or flying boats), and flexibly supported planing craft. The latter could simulate the new method found in the experiments for suppressing porpoising. In this study, the stability of the oscillatory motions was analyzed to see the effect of design variables on the inception of porpoising. The parametric study of flexibly supported float planes in the context of porpoising was a new contribution in the conceptual design of seaplanes
Hydroelastic response of concrete shells during impact on calm water
Many ocean structures located offshore are supported by large vertical concrete columns. High and steep storm waves – in the process of breaking – may induce large local slamming loads on these columns. The present work is related to the fundamental physics of the local hydroelastic shell response due to slamming. The concrete columns supporting typical offshore structures are large. The size means that full scale tests of a segment of the column is impractical and expensive. Model-scale testing in a wave tank is also challenging. Firstly, the scaling of structural properties need to adhere to the scaling laws of hydrodynamics. Secondly, the manufacturing of realistic Froude scaled elastic shell models is hard since curved shells carries loads by a combination of bending and membrane action. The challenge is to scale both the bending and membrane action properly. One part of this study shows how realistic Froude scaled elastic shells representing concrete shells can be designed. The second part of this study presents results from experimental and numerical analysis of drop tests. Numerical hydroelastic analyses of both the elastic model shells and the real concrete shells are presented. The results show that even large and thick concrete shells experience significant hydroelastic effects during slamming. The hydroelastic response of the concrete shells is dominated by only a few structural eigenmodes. This means that the calculated dynamic amplification factors, DAF, resemble those of one-degree-of-freedom mass–spring systems exposed to loads of finite duration. The structural responses are seen to significantly modify the hydrodynamic loads. This hydrodynamic load modification consists of the well-known added mass term but also a time dependent slam damping term which reduce the structural response when properly accounted for. Both terms are necessary to calculate the concrete shell response accurately.Hydroelastic response of concrete shells during impact on calm waterpublishedVersio
Breast cancer tumor growth estimated through mammography screening data
Introduction
Knowledge of tumor growth is important in the planning and evaluation of screening programs, clinical trials, and epidemiological studies. Studies of tumor growth rates in humans are usually based on small and selected samples. In the present study based on the Norwegian Breast Cancer Screening Program, tumor growth was estimated from a large population using a new estimating procedure/model.
Methods
A likelihood-based estimating procedure was used, where both tumor growth and the screen test sensitivity were modeled as continuously increasing functions of tumor size. The method was applied to cancer incidence and tumor measurement data from 395,188 women aged 50 to 69 years.
Results
Tumor growth varied considerably between subjects, with 5% of tumors taking less than 1.2 months to grow from 10 mm to 20 mm in diameter, and another 5% taking more than 6.3 years. The mean time a tumor needed to grow from 10 mm to 20 mm in diameter was estimated as 1.7 years, increasing with age. The screen test sensitivity was estimated to increase sharply with tumor size, rising from 26% at 5 mm to 91% at 10 mm. Compared with previously used Markov models for tumor progression, the applied model gave considerably higher model fit (85% increased predictive power) and provided estimates directly linked to tumor size.
Conclusion
Screening data with tumor measurements can provide population-based estimates of tumor growth and screen test sensitivity directly linked to tumor size. There is a large variation in breast cancer tumor growth, with faster growth among younger women
Case report of homozygous E200D mutation of PRNP in apparently sporadic Creutzfeldt-Jakob disease
Background: Inherited prion diseases are rare autosomal dominant disorders associated with diverse clinical presentations. All are associated with mutation of the gene that encodes prion protein (PRNP). Homozygous mutations with atypical clinical phenotypes have been described but are extremely rare.
Case presentation: A Chinese patient presented with a rapidly progressive cognitive and motor disorder in the clinical spectrum of sCJD. Investigations strongly suggested a diagnosis of CJD. He was found to carry a homozygous mutation at PRNP codon 200 (E200D), but there was no known family history of the disorder. The estimated allele frequency of E200D in East Asian populations is incompatible with it being a highly penetrant mutation in the heterozygous state.
Conclusion: In our view the homozygous PRNP E200D genotype is likely to be causal of CJD in this patient. Homotypic PrP interactions are well known to favour the development of prion disease. The case is compatible with recessively inherited prion disease
Site-specific reverse splicing of a HEG-containing group I intron in ribosomal RNA
The wide, but scattered distribution of group I introns in nature is a result of two processes; the vertical inheritance of introns with or without losses, and the occasional transfer of introns across species barriers. Reversal of the group I intron self-splicing reaction, termed reverse splicing, coupled with reverse transcription and genomic integration potentially mediate an RNA-based intron mobility pathway. Compared to the well characterized endonuclease-mediated intron homing, reverse splicing is less specific and represents a likely explanation for many intron transpositions into new genomic sites. However, the frequency and general role of an RNA-based mobility pathway in the spread of natural group I introns is still unclear. We have used the twin-ribozyme intron (Dir.S956-1) from the myxomycete Didymium iridis to test how a mobile group I intron containing a homing endonuclease gene (HEG) selects between potential insertion sites in the small subunit (SSU) rRNA in vitro, in Escherichia coli and in yeast. Surprisingly, the results show a site-specific RNA-based targeting of Dir.S956-1 into its natural (S956) SSU rRNA site. Our results suggest that reverse splicing, in addition to the established endonuclease-mediated homing mechanism, potentially accounts for group I intron spread into the homologous sites of different strains and species
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Dog Owners\u27 Perspectives on Canine Dental Health : A Questionnaire Study in Sweden
Periodontal disease is one of the most common diseases affecting dogs, with a reported prevalence of at least 80% in dogs over 3 years of age. However, there is a lack of studies regarding dog owners\u27 assessment of their dog\u27s dental health, and whether they perceive clinical signs often associated with periodontal disease, i.e., dental calculus, halitosis or mobile or lost teeth. A validated questionnaire survey was distributed to all Swedish dog owners with email addresses in the national registry (n = 209,263). The response rate was 32%. The survey questions concerned opinions and practices regarding canine dental health, including assessment of dental health parameters and dog owners\u27 ability to examine their dog\u27s mouth. A construct (α = 0.76) was used to investigate dog owners\u27 assessed symptoms of their dog\u27s dental health in relation to background factors. Half of the respondents rated their dog\u27s dental health as very good. However, one in four dog owners experienced difficulties when inspecting the dog\u27s teeth. The most common reason for this difficulty was stated to be an uncooperative dog. Almost half of the dog owners reported halitosis to some degree in their dog, and almost four in ten owners reported dental calculus. One in eight dogs had been previously anesthetized for dental cleaning, and one in 12 dogs had experienced problems with gum disease, according to the owners. Owners\u27 assessment varied significantly with the dog\u27s age, weight, breed, breed group, sex, and concurrent disease. Owner-related factors that influenced the assessment of the dog\u27s dental health were age, gender, education, county (urban/rural), and whether they were breeders or not. Dog owners with smaller dogs, older dogs and certain breeds predisposed to periodontal disease assessed their dog\u27s dental health as worse than their counterparts, which is in agreement with previously reported higher prevalence of dental disease in these groups. This indicates that dog owners are able to perform relative assessment of their dog\u27s dental health status. Our results also highlight the need for routine professional assessment of periodontal health, as well as education of dog owners and training of dogs to accept dental care procedures
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